Pharmacokinetics and dosage regimen of roxithromycin in adult healthy female subjects

Macrolides are a group of antibiotics produced by Streptomyces bacteria commonly used to treat bacterial infections, including gum infections, gingivitis, and stomach and intestinal ulcers. Roxithromycin is a macrolide antibiotic that effectively targets bacterial cells and inhibits their growth, promoting symptom relief and recovery. Despite this, there is limited research on roxithromycin pharmacokinetics and dosing regimens, particularly in healthy female volunteers from the local population. Thus, this study aimed to investigate roxithromycin's pharmacokinetic parameters and dose regimen in ten healthy female volunteers aged 18 to 30 years. Participants received an oral dose of 300 milligrams of roxithromycin, and blood samples were collected at various intervals for 48 hours. Pharmacokinetic parameters were assessed using two open compartmental models and high-performance liquid chromatography (HPLC). The results showed that the Cmax of roxithromycin was 10.13 ± 0.43 µg/mL, attained at a time to reach tmax of 2.42 ± 0.34 hours. Moreover, the drug exhibited a volume of distribution of 1.38 ± 0.55 L/kg, an elimination half-life of 34.95 ± 22.51 hours, and a total body clearance of 0.04 ± 0.01 L/hr/kg. In accordance with these results, the calculated dosage regimen for 24-hour intervals was 975 milligrams as a priming dose and 372 milligrams as a maintenance dose. In conclusion, this study found that the elimination half-life (t1/2 β) of roxithromycin was higher than literature values, leading to less clearance and ultimately increased Cmax, tmax, and area under the curve (AUC) values of the orally administered drug, indicating the need for dose adjustment in patients.